This disclosure relates generally to optoelectronic devices and more particularly to a light emitting diode (LED) bulb having high and low beams and to a lighting system constructed using the (LED) bulb.
Light emitting diode (LED) bulbs have been developed that are interchangeable with conventional light bulbs having incandescent and fluorescent light sources. Some light bulbs, such as H4 lamps used in automotive applications, can include a low beam light source and a high beam light source. These light bulbs can also include a reflector for collimating the light emitted by the light sources into light beam having desired patterns and angles of reflection. For example, in the high beam mode, light can be reflected in a beam of parallel rays located both above and below the x-axis (horizontal axis). In the low beam mode, light can be reflected in a beam of scattered rays extending in a direction below the x-axis.
Referring to FIG. 1, a prior art dual beam light bulb 10 includes a base 12 having contact pins 14, a driver 16 having a driver housing 18, and a transparent lens 20 having a mirrored tip 22. The light bulb 10 also includes a low beam filament 24, a high beam filament 26 and a shutter 28 on the low beam filament 24. The shutter 28 is configured to define the shape of the low beam light pattern and to prevent light from the low beam filament 24 from reflecting during the high beam mode.
As shown in FIGS. 2A-2C, the light bulb 10 can be mounted to a reflector 30 as a component of a lighting system 40, such as on a motor vehicle. As shown in FIG. 2A, in the high beam mode, light rays 32 are reflected from the reflector 30 to form a high beam 36 composed of parallel spaced rays reflected both above and below the horizontal axis 34. As shown in FIG. 2B, in the low beam mode, light rays 32 are reflected from the reflector 30 to form a low beam 38 of scattered rays reflected downward with respect to the horizontal axis 34. As shown in FIG. 2C, the high beam 36 is formed by the entire surface area of the reflector 30, while the low beam 38 is formed by only a portion of the surface area of the reflector 30 in an area defined by the shutter 28.
Dual beam (LED) light bulbs have also been designed using (LED) light sources. In some of these (LED) light bulbs, a single (LED) light source is configured to emit light in a first direction during the low beam mode, and in a second direction during the high beam mode. However, this type of (LED) light bulb does not function efficiently with prior art reflectors particularly in retrofit applications. For example, the low beam typically has no clear-cut boundaries, and the brightness of the low beam is less than with a halogen bulb.
In view of the foregoing, there is a need in the art for a dual beam (LED) bulb and lighting system having improved high and low beam patterns. There is also a need for a dual beam LED bulb that can be used with prior art reflectors and which can be retrofitted into conventional lighting systems including automotive systems. The present disclosure is directed to a light emitting diode (LED) bulb and lighting system having low and high beam patterns with improved brightness and definition, and which can be retrofitted to conventional reflectors.